Photo by Ant Rozetsky

Japanese manufacturer Sumitomo Electric Industries has opened the UK’s first HVDC subsea cable factory at the Port of Nigg on the Cromarty Firth. The £350 million plant, which sits within the Inverness and Cromarty Firth Green Freeport, will make the high voltage direct current cables needed to carry power from offshore wind farms to centres of demand. It will also make the inter-array cables that link turbines together.

The facility covers 58,000 square metres on a 15-hectare site and will produce 525kV XLPE HVDC subsea transmission cables. Sumitomo says HVDC cables can carry a much higher volume of usable energy from offshore wind farms than conventional high voltage alternating current cables, BBC Scotland reports. The cables will feed the planned network of subsea links between Scotland and England.

Sumitomo says the factory will directly create more than 200 skilled local jobs, with a projected 400 or more across the wider UK supply chain. Operators are being trained through a “Train the Trainer” model and programmes in Japan.

Osamu Inoue, president of Sumitomo Electric Industries, said the factory “will serve as a vital production base supporting the strengthening of the UK’s transmission infrastructure, the expansion of renewable energy deployment, and the delivery of a stable and reliable energy supply for generations to come.” Sumitomo Electric Group chairman and CEO Masayoshi Matsumoto said the company would “further deepen and strengthen our relationships with local stakeholders through hundreds of job creation, workforce development along with significant sustainability contributions.” According to the Scotland Office, the factory means the UK is now among G7 countries able to manufacture its own HVDC cables.

Anchored by grid contracts

The investment was announced in April 2023, backed by transmission projects that gave Sumitomo the long-term demand it needed to commit. SSEN Transmission’s proposed Shetland 2 link, for which Sumitomo was named preferred bidder, underpinned the decision. Rob McDonald, managing director of SSEN Transmission, said the company was “proud of the role our proposed Shetland 2 subsea cable project played as an anchor for this investment.”

National Grid has since awarded Sumitomo the HVDC cable supply contract for Sea Link, a 140km subsea connection between Suffolk and Kent, which Ocean News reported would be made at Nigg. Carl Trowell, executive president of global capital at National Grid, said Sumitomo’s “decision to invest in this facility reflects the confidence that long-term investment can provide.”

Easing a global bottleneck

The opening comes as developers and grid operators compete for scarce cable manufacturing capacity. In late 2024, Offshore magazine reported that three European manufacturers, NKT, Prysmian and Nexans, held around three-quarters of the HVDC cable market. It added that some factories had no free production slots before 2028, and that National Grid was making upfront payments to secure capacity.

Energy Secretary Miatta Fahnbulleh said: “Making subsea cables in Scotland will help us tackle the bottlenecks that block electricity from being transported across the country.” The government also highlighted the factory’s opening in its announcement on the Jackdaw gas field as evidence of investment in new energy industries.

Nigg may not be alone for long. XLCC is developing a separate HVDC cable factory on a former coal yard at Hunterston in North Ayrshire, backed by the Scottish National Investment Bank and the National Wealth Fund, according to a Just Transition Commission case study. No production date has been given.

Public backing

First Minister John Swinney, who attended the opening alongside Douglas Alexander, said the Scottish Government had “invested £24.5 million in its construction to support hundreds of well-paid jobs in the Highlands.” He told the BBC: “As the first factory of its kind in the UK, it will help unlock our enormous offshore wind potential while bolstering energy security.”

Scottish Secretary Douglas Alexander said: “Scotland is helping to solve one of the biggest challenges in our transition to clean energy, connecting offshore wind to where it’s needed most.” He pointed to the £25 million of UK Government seed funding behind the green freeport, which he said shows “exactly what ‘growth in every postcode’ looks like in practice.”

Angus Campbell, chair of Highlands and Islands Enterprise, described it as “one of the biggest inward investments ever made in the Highlands and Islands,” adding: “The fact that high-voltage subsea cables will be manufactured here in the Highlands and deployed in our coastal waters is hugely significant.”

SSEN Transmission, which plans to invest around £29 billion over the next five years, believes there is more to come. McDonald said that “with continued collaboration and greater certainty around future grid investment, planning decisions and the long-term pathway for Scotland’s renewable ambitions, there is potential to attract even more investment, skills, and jobs.”